The invention relates to a valve for controlling fluids as defined by the preamble to claim 1. From European Patent Disclosure EP 0 477 400 A1, one such valve is already known, which is actuatable via a piezoelectric actuator. This known valve has an arrangement for an adaptive mechanical tolerance compensation, effective in the stroke direction, for a travel transformer of the piezoelectric actuator, in which the deflection of the piezoelectric actuator is transmitted via a hydraulic chamber.
The hydraulic chamber, which functions as a so-called hydraulic step-up means, encloses a common compensation volume between two pistons defining this chamber, of which one piston is embodied with a smaller diameter and is connected to a valve member to be triggered, and the other piston is embodied with a larger diameter and is connected to the piezoelectric actuator.
The hydraulic chamber is fastened between the two pistons in such a way that the actuating piston of the valve member, which piston is retained in its position of repose by means of one or more springs relative to a predetermined position, executes a stroke that is increased by the step-up ratio of the piston diameter when the larger piston is moved a certain travel distance by the piezoelectric actuator. The valve member, piston and piezoelectric actuator are located one after the other on a common axis.
Via the compensation volume of the hydraulic chamber, tolerances caused by temperature gradients in the component or different coefficients of thermal expansion of the materials used and possible settling effects can be compensated for without causing a change in position of the valve member to be triggered.
Compensating for changes in length of the piezoelectric actuator, the valve member or the valve housing by means of the hydraulic chamber disposed between two pistons requires a complicated construction, however, and is problematic in terms of the incident leakage losses and the refilling of the hydraulic chamber.
The object of the invention is to create a valve for controlling fluids having a piezoelectric unit in which in particular a tolerance compensating element is achieved for compensating for elongation tolerances of the piezoelectric unit and/or other valve components, which occupies little space and is simple in design.
The valve for controlling fluids according to the invention as defined by the characteristics of the body of claim 1 has the advantage that it operates at a high natural frequency, since a direct force transmission via the deflection element is provided without a step-up, with which the natural frequency decreases quadratically.
A significant advantage of the invention is also that the valve, with the arrangement according to the invention of the piezoelectric unit, deflection element and tolerance compensating element, has a compact structure.
The tolerance compensating element, in particular for elongation tolerances dictated by temperature changes, is achieved economically according to the invention by simple mechanical means.
Further advantages and advantageous features of the subject of the invention can be learned from the description, drawing and claims.